The present invention relates to an eccentric screw pump for conveying liquids from bore holes, especially oil well bores. The pump includes an eccentric screw, a stator associated with said screw and located at the deepest point of a riser, and an aboveground drive and bearing unit, the drive shaft whereof is connected with a rod linkage by means of a rotating joint which transmits torque and axial force, with the rotor being suspended from said rod linkage. The eccentric screw shall be referred to hereafter as the rotor.
In known eccentric screw pumps of this type the necessary discharge pressure is produced by a single conveying unit consisting of a stator with a rotor located therein. The stator may be composed of several individual stators. The conveying unit is arranged at the deepest point of the riser, with filters and a suction pipe being provided optionally below the stator. The rod linkage carrying the rotor is fastened by means of a coaxial screw joint to the drive shaft of the aboveground drive and bearing unit, said drive shaft being of massive constructon. The rotor is positioned within the stator by means of rod shaped adaptors mounted on the upper end of the linkage.
When the rotor becomes worn, the linkage, which may be several hundred meters long, must be disassembled, while in the case of a worn stator both the riser and the linkage must be removed. It is a further disadvantage that, because of the aforementioned adaptors in the rod linkage, the positioning of the rotor with respect to the stator associated with it is possible in discrete steps only.